rs1553612143

Variant names:

• chr3-33068248-G-A
• rs1553612143
• NM_000404.4:c.439C>T

Variant summary

Our verdict is Pathogenic. The variant received 15 ACMG points: 15P and 0B. PM1 PM2 PP2 PP3_Moderate PP5_Very_Strong

The NM_000404.4(GLB1):​c.439C>T​(p.Leu147Phe) variant causes a missense change. The variant allele was found at a frequency of 0.00000137 in 1,461,710 control chromosomes in the GnomAD database, with no homozygous occurrence. In-silico tool predicts a pathogenic outcome for this variant. Variant has been reported in ClinVar as Likely pathogenic (★★). Synonymous variant affecting the same amino acid position (i.e. L147L) has been classified as Likely benign.

• Frequency:
  • Genomes: not found (cov: 32)
  • Exomes 𝑓: 0.0000014 (0 hom.)
• Consequence: GLB1 NM_000404.4 missense
• Clinical Significance: Likely pathogenic criteria provided, multiple submitters, no conflicts P:2
• Conservation: PhyloP100: 6.24
• Publications: 0 publications found

Genes affected

GLB1 (HGNC:4298): (galactosidase beta 1) This gene encodes a member of the glycosyl hydrolase 35 family of proteins. Alternative splicing results in multiple transcript variants, at least one of which encodes a preproprotein that is proteolytically processed to generate the mature lysosomal enzyme. This enzyme catalyzes the hydrolysis of a terminal beta-linked galactose residue from ganglioside substrates and other glycoconjugates. Mutations in this gene may result in GM1-gangliosidosis and Morquio B syndrome. [provided by RefSeq, Nov 2015]

GLB1 Gene-Disease associations (from GenCC):

• GM1 gangliosidosis

  Inheritance: AR Classification: DEFINITIVE Submitted by: Myriad Women’s Health, ClinGen
• GM1 gangliosidosis type 3

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, Labcorp Genetics (formerly Invitae), G2P, Genomics England PanelApp
• mucopolysaccharidosis type 4B

  Inheritance: AR Classification: DEFINITIVE, STRONG, SUPPORTIVE Submitted by: Orphanet, ClinGen, Labcorp Genetics (formerly Invitae), Genomics England PanelApp
• GM1 gangliosidosis type 1

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Genomics England PanelApp, Orphanet
• GM1 gangliosidosis type 2

  Inheritance: AR Classification: STRONG, SUPPORTIVE Submitted by: Orphanet, Genomics England PanelApp

ACMG classification

Our verdict: Pathogenic. The variant received 15 ACMG points.

• PM1: In a hotspot region, there are 11 aminoacids with missense pathogenic changes in the window of +-8 aminoacids around while only 0 benign, 2 uncertain in NM_000404.4
• PM2: Very rare variant in population databases, with high coverage
• PP2: Missense variant in the gene, where a lot of missense mutations are associated with disease in ClinVar. The gene has 110 curated pathogenic missense variants (we use a threshold of 10). The gene has 24 curated benign missense variants. Gene score misZ: 0.79419 (below the threshold of 3.09). Trascript score misZ: 1.1264 (below the threshold of 3.09). GenCC associations: The gene is linked to mucopolysaccharidosis type 4B, GM1 gangliosidosis, GM1 gangliosidosis type 2, GM1 gangliosidosis type 3, GM1 gangliosidosis type 1.
• PP3: MetaRNN computational evidence supports a deleterious effect, 0.874
• PP5: Variant 3-33068248-G-A is Pathogenic according to our data. Variant chr3-33068248-G-A is described in ClinVar as Likely_pathogenic. ClinVar VariationId is 522669.Status of the report is criteria_provided_multiple_submitters_no_conflicts, 2 stars.

Transcripts

RefSeq

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	MANE	Protein	UniProt
GLB1	NM_000404.4	c.439C>T	p.Leu147Phe	missense_variant	Exon 4 of 16	ENST00000307363.10	NP_000395.3

Ensembl

Gene	Transcript	HGVSc	HGVSp	Effect	Exon rank	TSL	MANE	Protein	Appris	UniProt
GLB1	ENST00000307363.10	c.439C>T	p.Leu147Phe	missense_variant	Exon 4 of 16	1	NM_000404.4	ENSP00000306920.4

Frequencies

GnomAD3 genomes Cov.: 32

GnomAD4 exome AF: 0.00000137 AC: 2 AN: 1461710 Hom.: 0 Cov.: 31 AF XY: 0.00000138 AC XY: 1 AN XY: 727160

African (AFR) AF: 0.00 AC: 0 AN: 33480

American (AMR) AF: 0.00 AC: 0 AN: 44720

Ashkenazi Jewish (ASJ) AF: 0.00 AC: 0 AN: 26132

East Asian (EAS) AF: 0.00 AC: 0 AN: 39698

South Asian (SAS) AF: 0.0000116 AC: 1 AN: 86250

European-Finnish (FIN) AF: 0.00 AC: 0 AN: 53398

Middle Eastern (MID) AF: 0.00 AC: 0 AN: 5764

European-Non Finnish (NFE) AF: 8.99e-7 AC: 1 AN: 1111886

Other (OTH) AF: 0.00 AC: 0 AN: 60382

GnomAD4 genome Cov.: 32

ClinVar

Significance: Likely pathogenic

Submissions summary: Pathogenic:2

Revision: criteria provided, multiple submitters, no conflicts

Submissions by phenotype

GM1 gangliosidosis;C0086652:Mucopolysaccharidosis, MPS-IV-B Pathogenic:1

May 22, 2023

Labcorp Genetics (formerly Invitae), Labcorp

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

In summary, the currently available evidence indicates that the variant is pathogenic, but additional data are needed to prove that conclusively. Therefore, this variant has been classified as Likely Pathogenic. Algorithms developed to predict the effect of sequence changes on RNA splicing suggest that this variant may disrupt the consensus splice site. Advanced modeling of protein sequence and biophysical properties (such as structural, functional, and spatial information, amino acid conservation, physicochemical variation, residue mobility, and thermodynamic stability) performed at Invitae indicates that this missense variant is expected to disrupt GLB1 protein function. ClinVar contains an entry for this variant (Variation ID: 522669). This missense change has been observed in individual(s) with GM1-gangliosidosis (PMID: 33737400). In at least one individual the data is consistent with being in trans (on the opposite chromosome) from a pathogenic variant. This variant is not present in population databases (gnomAD no frequency). This sequence change replaces leucine, which is neutral and non-polar, with phenylalanine, which is neutral and non-polar, at codon 147 of the GLB1 protein (p.Leu147Phe).

Infantile GM1 gangliosidosis Pathogenic:1

Dec 03, 2017

Genomic Research Center, Shahid Beheshti University of Medical Sciences

Significance: Likely pathogenic

Review Status: criteria provided, single submitter

Collection Method: clinical testing

Computational scores

Source: dbNSFP v4.3

Name	Calibrated prediction	Score	Prediction
AlphaMissense	Benign	0.33
BayesDel_addAF	Pathogenic	0.38	D
BayesDel_noAF	Pathogenic	0.31
CADD	Uncertain	25
DANN	Uncertain	1.0
DEOGEN2	Benign	0.0	.;.;D
Eigen	Uncertain	0.58
Eigen_PC	Uncertain	0.54
FATHMM_MKL	Pathogenic	0.98	D
LIST_S2	Benign	0.0	.;.;D
M_CAP	Pathogenic	0.41	D
MetaRNN	Pathogenic	0.87	D;D;D
MetaSVM	Pathogenic	1.1	D
MutationAssessor	Benign	0.0	.;.;.
PhyloP100		6.2
PrimateAI	Uncertain	0.57	T
PROVEAN	Uncertain	-3.3	D;D;D
REVEL	Pathogenic	0.82
Sift	Uncertain	0.0050	D;D;D
Sift4G	Uncertain	0.012	D;D;D
Vest4		0.81
ClinPred		0.99	D
GERP RS		5.3
gMVP		0.90
Mutation Taster		=36/64	disease causing (ClinVar)

Splicing

Name	Calibrated prediction	Score	Prediction
SpliceAI score (max)		0.20		Details are displayed if max score is > 0.2
DS_DL_spliceai		0.20		Position offset: -18

Find out detailed SpliceAI scores and Pangolin per-transcript scores at spliceailookup.broadinstitute.org

Other links and lift over

dbSNP: rs1553612143; hg19: chr3-33109740;